Frequency dependent charge pumping — A defect depth profiling tool?

We investigate the validity of using frequency-dependent charge pumping (FD-CP) to determine bulk defect depth distributions. Using simple physical arguments we conclude that: (1) the effective tunneling length to a bulk defect can be very different than its actual physical depth, and (2) only a fraction of detrapping charge may contribute to the CP current (I_CP) resulting in analysis errors. Thus, the relationship between frequency and defect depth is much more complex than what has been previously reported.